Hackers discover flaws in smart cards
Transit agencies need not panic
By Zane Ewton
The Mifare smart card fare collection system came under fire when computer-security researchers in the Netherlands proved they could crack the security code with a personal computer and about $100 worth of hardware.
The Mifare technology is widely used in transit applications as it is simple to configure and processes information quickly. The simple security set-up also enables faster transaction times.
Once the researchers published their results in 2008, news reports claimed transit systems across the U.S. and Canada could stand to lose tens of thousands of dollars to fare fraud.
A breach in fare collection security is similar to printing counterfeit money. With the right access an individual can change card balances, create fake cards and cause headaches for other riders. This would lead to lost revenues and customer service issues for transit agencies.
However transit agencies should not panic says Doug Van Blaricom, systems engineer for Acumen Building Enterprises, Inc., Oakland, CA.
“Hacking into a smart card system or counterfeiting access cards is not easy,” he says. “Not everyone is an MIT student. The equipment may be cheap, but this process involves a high level of expertise and a lengthy investment of time. It is just not that simple.”
According to Van Blaricom the hacker would need to create a tool with a laptop or another reader to interact with the smart card and the reader, and analyze the information processed through every failed transaction attempt. The failed attempts could give clues to what the correct keys are and then process that information into a counterfeit card.
“To their credit, these researchers cracked the system just as a warning,” he says. “This uncovered the security system’s risks. However, the doomsday scenario is not that anyone can just get a card reader on Ebay and start counterfeiting smart cards.”
A transit agency that struggles to get riders through its gates quickly relies on a fare collection system that can process transactions as rapidly as possible. The nature of contactless fare collection creates a situation where incomplete transactions occur. The faster the transaction, the less likely a rider will remove the card before the transaction is complete.
“It is not really fair to blame the smart card company,” says Van Blaricom. “This is really a case of thinking simpler is better, but in technology security that is not the case at all.”
He says the benchmark for length of transaction time is 300 milliseconds. Security measures increase the time exponentially.
During the transaction period the card receives power from the radio frequency field. As the card enters it has to power up, initialize communication, then perform read and write operations, all within the 300 millisecond window. A variance in transaction times by milliseconds does not appear to be a problem, but the faster the better. Less than 300 milliseconds in transaction time improves the transaction success rate, and moves passengers on board faster.
The Mifare system is easy to use because the installed reader chip had special memory locations where data is written but not read. This was used to authenticate the cards, but the method required only one key to protect the whole system. When an individual cracks the key, they have gone a long way towards hacking into the entire system.
According to Van Blaricom a more secure system relies on key diversification. This provides a route key in the system, but the keys that are attached to each issued card are derived from the route key. The issued card receives essentially its own unique serial number. The master key can combine with the card serial number to create a combination that is unique but still readable to the card reader.
“If someone were to go through the reverse engineering as the researchers did with the Mifare system, they would only get down to one specific card,” says Van Blaricom. “The hackers would need to go back and work through every card to get its special diversified key.”
A fare collection system with simple security keys is similar to a computer with poor passwords. Setting a password as ABCD is very easy to crack.
According to Van Blaricom one of the arguments against contactless smart cards was that the exchange of information over the airwaves would be easy to listen in on. While that is true, he says the information would not make any sense. The card identifies the reader with a random number that signals the secret key, which in turn prompts the reader to respond. Anyone listening in would only hear the random number, which essentially means nothing. The reader transfers an encrypted result that is nearly impossible to understand.
“The Mifare system is not obsolete and as technology evolves the system will become more secure,” says Van Blaricom. “Transit agencies should always focus on improved security, and rely on systems that do not require a complete rebuild in order to move forward.” BR